We will use two approaches to the problem of characterizing the progression to malignancy of cultured human epithelial cells. First, we will continue studies characterizing the properties of human mammary epithelial cells derived from specimens representing various stages of progression (i.e., reduction mammoplasties, peripheral mastectomy tissue, primary and metastatic carcinomas). We will continue studies characterizing invasion into stromal monolayers and generation of drug resistance. Our second approach is to develop culture conditions for another human epithelial system in order to evaluate organ specific vs. carcinoma specific changes. We will continue our studies with colon cultures in order to optimize nutrient additives as well as to develop a system for subculture by disassociating into single cells.